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View Full Version : Lumpy Low to Midrange running and flat spot.



thetroublemaker
Wednesday 18th October 2006, 18:39
Here are the facts.

My Volvo is a 1996 T5 with 157000 miles on the clock. It is an OBD-II car.

It idles perfectly, however is lumpy when cold/at light throttle at between 2000 and 2500 rpm, with a pronounced flat spot at all temperatures between about 3200 and 3700-3800 rpm.

EDIT - when i say lumpy its more lots of little flat spots more than a misfire.......

I have replaced HT leads (all), rotor arm, distributor cap, and run a tank of injector cleaner through it.

I have also changed the oil and oil/air filters.

The plugs were changed at the 150k service, and visual inspection suggests they are working fine.

The lambda light comes on and goes off as it should (i.e. the bulb is still there).

I am still not 100% convinced the hissing noise from the turbo is correct, which may be relavent. If i toe the car from say 2000rpm in third the gauge will go to 3/4 of the way into the white and then drop off after a second or so to 1/2 way approx where it will maintain. The hissing noise seems to go after the turbo's reached boost - could this be a vacuum line "discarging"???

What steps should i take to solve/troubleshoot this problem. :)

colnotts
Wednesday 18th October 2006, 23:45
sounds like mine mate. had my codes read and it looks like mine is the maf sensor. mine started out like yours and just got worse now is will run for 30 secs then it just cuts out take it and have the codes read bet it will be the same as mine.

col

thetroublemaker
Thursday 19th October 2006, 00:12
cheers col.

i would have expected the lambda light to be on though to be fair...........:)